Question

If a recombinant DNA bearing gene for ampicillin resistance is transferred into E. coli cells and the host cells are spread on agar plates containing ampicillin, then

• A. both transformed and untransformed recipients cell will die
• B. both transformed and untransformed recipients cells will grow
• C. transformed recipients cells will grow and untransformed cell will die
• D. transformed recipients cells will die and untransformed recipients cells will grow

Answer 1

Answer: (C)

Transformation is a procedure through which a piece of DNA is introduced in a host bacterium. DNA bearing ampicillin resistance gene (transformed recipients cells). When introduced into the plate containing ampicillin will grow while DNA not bearing ampicillin resistance gene (untransformed recipient cells) will die. Normally, the genes encoding resistance to antibiotics such as ampicillin, chloramphenicol, tetracycline or kanamycin, etc. are considered useful selectable markers for E. coll. The normal E.coli cells do not carry resistance against any of there antibiotics.